In modern day digital equipment, there has been developing a greater and greater density of packaging on printed circuit boards, and a higher density of printed circuit boards in computer and digital cabinetry, with larger and more complex integrated circuit package components. In this situation, there have been numerous ways developed to reduce the generation of internal heat and to carry away the excessive heat buildup.
One of the basic ways of doing this has been to develop metallic fins and other heat conducting means by which cooling air can be used to carry away the accumulated internal heat within the integrated circuit packages that are used on the printed circuit boards.
A major problem has been to provide for the maximization of the heat dissipation and at the same time to be economically feasible, while additionally providing for ease of application to areas which are restricted in space and cooling capacity. These problems further require ease of attachment for a maximum of heat dissipation to integrated circuit packages having a limited area or encumbered area of heat sink attachment.
Thus, in order to provide an economically feasible heat dissipation from small compact areas or from areas encumbered or limited because of electrical or mechanical requirements, there has been developed a heat sink device for attachment to the top of an integrated circuit package comprised of cooling fins mounted on a spreader plate, but with a reduction of area at the base of the spreader plate, the radial metallic fins being configured to form a central orifice area whereby cooling air can impinge into the orifice area and outwardly pass by the fins to provide the required cooling action.
Very often the surfaces of integrated circuit packages use perimeter areas around the top edges to provide space for electrical test points and electronic components. Thus special types of heat sink mountings may be required to accommodate these conditions. By including a reducing taper in the spreader plate of the heat sink device, the dissipating fins comprise a much larger surface area, and thus a more effective heat transfer, than would otherwise be possible on an integrated circuit package with an encumbered or limited area of heat sink attachment.